It is common for medical patients to self-inject medicines. For reasons of convenience and/or reduction of cost, patients generally desire that they be able to inject or otherwise administer medicines to themselves or others in their homes, offices, or other locations besides a doctor's office, clinic, hospital, or other medical facility that may be inconvenient and/or expensive to visit. However, some medicines, including those which may be self-injected, are a mixture, suspension, or other combination of two substances. Furthermore, often such medicines must be injected immediately or shortly after the two substances are combined. In some cases, one of the two substances is a diluent and the other is a powder, microspheres, or similar substance. In other cases, each of the two substances to be combined is a liquid.
There are existing devices for combining two substances for self-injection. U.S. Patent Publication No. 2005/0113747 to Moir discloses a device having two tubular bodies, two chambers configured to communicate with each other, and a double-ended needle held in position by a guide member. The double-ended needle is between the two chambers such that when the two tubular bodies are slid toward each other, the respective ends of the needle pass into the two chambers.
Another existing device is disclosed in U.S. Pat. No. 7,077,835 to Robinson et al. This patent discloses a device configured to reconstitute a liquid for medical use by combining a first liquid medium contained in a first vessel and a second medium, such as a drug in solid form, contained in a second vessel. The device further includes a movable member for applying a force to cause the first liquid medium to be delivered at a controlled rate from the first vessel to the second vessel. The device is further configured to receive a needle for transferring the liquid from the device.